This invention relates to fluid fittings for connecting tubes and pipes and, more particularly, to pressure fittings that can be disconnected and re-used.
Fittings are commonly used to connect metal or plastic tubes and pipes to each other in a variety of applications such as in the aerospace industry to convey fuel, hydraulic control fluids and the like in an aircraft, on board ship, in construction, in water systems or in a space vehicle. These types of tubes and pipes are commonly laid into narrow and crowded areas alongside other pipes and electrical wiring. The use of pipe and tube fittings during original installation, retrofitting or repair operations can be very difficult and time consuming and may be subject to environmental restrictions in terms of working space, maximum heat tolerance, the presence of potentially explosive gases, and prohibition against corrosive smoke, fume or abrasive fluxes.
It is well-known that the quality of a weld joint depends a lot upon the skill of the welder. Even a highly skilled welder may not be able to perform at his best when working in a cramped space under some of the restrictive conditions described above. This is why swaged joints are favored. However, swaging tools such as the one described in U.S. Pat. No. 5,305,510 Croft et al.; U.S. Pat. No. 5,308,394 Hyatt et al.; and U.S. Pat. No. 5,592,726 Suresh are bulky and may not be appropriate for use in cramped quarters.
In many systems, fluid pressures and temperatures can vary greatly between and even during duty cycles. Fluid temperature variations will cause both pipe and tube fittings to expand and contract. The disproportionate expansion of adjacent structures can lead to leakage or other degredation of the joint. Many of the prior art designs mentioned are not specifically made to be reusable, making repairs, adjustments and replacements even more costly.
This invention results from attempts to develop a new type of pipe and tube fitting particularly adapted for use under very restrictive environmental and space conditions, which is reusable and which can accommodate dynamic fluctuations in fluid temperatures and pressures.
The principal and secondary objects of this invention are:
To provide a non-chemical and re-usable fitting for joining tubes and pipes that can create a highly reliable joint without requiring special skills, bulky specialized or special post-installation testing can be installed in extremely cramped quarters and without generating any heat, smoke, fumes or effluents that could be detrimental to workers or the surrounding equipment;
To provide a joint that can withstand high degrees, and large variation in temperature and pressure;
To provide for the connection of pipe or tube components without requiring precise alignments or adjustments, and which can even be installed blindly in very awkward or hard to reach spaces; and
To provide a non-bulky, simple-to-use tool and method of use for installing an improved joint on existing piping.
These and other valuable objects are achieved by a fitting comprising a female coupling to be engaged by the end of a pipe or tube, and having an axially split wall and tapering, threaded outer surface. A commensurately threaded nut is used to cinch the split segments of the coupling upon the pipe end. A first O-ring, collar or other similar sealing component is provided in order to either provide additional sealing power, or to accommodate slight differences in the geometry or diameters of pipes or tubings. A reinforcing ring or flange is provided at the end of the threaded section of the coupling to act as both a stop point for the nut and a grabbing surface for a wrench, pliers, vise or hands. An additional pair of sealing components is provided for placement in a pair of channels scored onto the pipe or tube end. A first sealing ring of resilient material provides an effective seal against low pressure leaks. A second sealing ring made of the same material as the pipe or tube is provided to prevent unacceptable deformation of the coupling wall, to more closely match the thermal expansion of the fitting, and to provide for a decrease in pressure during high pressure leakage. An adjustable tool for scoring the pipe in-situ has two pair of cooperating scoring wheels. Each wheel has a pair of parallely spaced apart circular scoring bits.